Study On Characteristics Of Sandstone Diagenesis And Reservior From Yingcheng Formation In Jinshan Gas Field

Yingcheng Formation is a potential reservoir in Jinshan gas field; it is the targetreservoir of the research. This paper studies the characteristics of petrologic, diagenesisand reservoir. In addition, the factors impacted on the reservoir are analyzed. To providetheoretical support for further oil and gas exploration, so as to improve the success rate ofdrilling, reduce the risk of exploration, to improve economic efficiency has importantsignificance.In this paper, rock types of this area are determined by use of thin-sectionidentification, cast thin-section analysis, scanning electron microscope and X-diffraction,combined with the description of rock core. There are lithic arkoses, which are mid-coarsegrain, coarse grain structure and poor sorting. The degree of roundness is mainlysub-angular to sub-rounded; interstitial matters are ainly the matrix.Main types of diagenesis include the compaction, the pressure solution, thecementation, the dissolution, the metasomatism and the alteration， meanwhile thecompaction and the pressure solution, causing the intergranular pores are not developed，cementation are more obvious, various of cements, and the complex cementation stageseriously affect the pore characteristics of reservoir; at the same time dissolution is bad,the value of secondary pores is not high, these are reasons that the porosity is poor;According to clay mineral assemblages, Emanon in the mixed-layer smectite ratio and thetypes of particle contact and so on, to determine rocks in the diagenetic phase middle A. There are primary intergranular pores (36.9%)，intragranular dissolved pores (51.1%),expand intergranular pores (3.9%), micropores (6.9%) and moldic pores (1.3%). Planeporosity of the sandstones is mainly low-grade, pore diameter is mainly a relatively smalllevel pore, pore throat width is mainly thin throat level, Porosity of Yingcheng Formationis based on ultra-low porosity; permeability is mainly ultar-low permeability andextra-low permeability.The analysis shows that the sandstone reservoir of the Yingcheng Formation isimpacted by the diagenesis. Due to compaction and cementation, the porosity andpermeability are reduced with increasing of depth. At the depth of2310-2450m, porosityand permeability of well Jin1increased abnormally, combined with the study ofpetrography, this range is the location of dissolution, forming a large number of secondarypores, causing the porosity and permeability of sandstones increasing...